Aspirator apparatus



June 19, 1928. 1,674,377

I C. G. SMITH ASPIRATOR APPARATUS Filed Sept. 4, 1924 ivwercZow ('i'zarzes 6. smzvzh,

Patented June 19, 1928.

v 1,674,372 outree STATES PATENT: "@FFIQE.

.cmmis G. SMITH, or iirnnronii, MASSACHUSETTS, Ass'IoNon, BY Mnsnn' ASSIGN- MENTS, T CAMBRIDGE LABORATORIES, INC., 01 CAMBRIDGE,.MASSACHUSETTS,' A.

CORYORATION OF MASSACHUSETTS.

* ASPIRATOR APPARATUS.

Application filed September 4, 1924. Serial No. 735,817.-

In aspirator apparatus for circulating a' gaseous fluid with a propellent vapor havlng a molecular weight greater than that of the gaseous fluid, such as'refrigerator systems employing mercury as the propellant and water as the refrigerant, the energy losses are so great that apparatus of this character has not become commercial notwithstanding its apparent theoretical possibilities. 1 l0 occur in the aspirator and that they can be largely eliminated by super-heating the propellent vapor in the aspirator or before entering the aspirator. l propelleut vapor both its drift velocity through the aspirator and its molecular velocity are increased. Owing to the increased drift velocity the density of the jet may be decreased for a given amount of work, there- 0 by economizing in the quantity of propellent vapor required. Owing to the increased molecular velocity, and also to the decreased density, the mean free path of the molecules is increased, and the two vapors diffuse into each/other ate more rapid rate. However the most important feature of the invention consistsin bringing the molecular velocity of the heavier propellent vapor up 'to approximately the molecular velocity of the vapor to be propelled, thereby bringing the drift velocity of the propelled vapor up to its maximum theoretical value and eliminating losses heretofore militati-ng against eificient operation.

For the purpose of illustration one concrete embodiment of the invention is illustrated in the accompanying drawings in which. the figure is a diagrammatic representation of a refrigerating system' pomprising a boiler -1, an aspirator 2, an evaporator or cooler 3', a

condenser 4, a propellent vapor conduit '5, leading from the boiler to the aspirator, a refrigerant vapor conduit 6 leading from the cooler to the aspirator, .a propellent 4 liquid duct 7 leading from the 'co'ndenser to the boiler, and a refrigerant liquid. duct 8 leading from the condenser to the cooler. The propeHent liquid 9 (e. g. mercury) stands in the conduit 7 at a height depending 9 upon the pressure in the boiler, and the re-.

frigerant liquid 10 (e. g. water) stands above the column of mercury. The shape ,of the 1 construction 11 ofthe aspirator may beadjusted to the different conditions, no attempt V I have discovered that the principal losses 4 By superheating the having beeuinade show any exact shape. It will be understood that boththe; propellent and refrigerant vapors are condensed together and that the propellant settles to the bottom by virtue of its higher specific gravity. A cooling jacket 12' isfshown merely to indicate that the condenser may be cooled and not to restrict the disclosur to any particular cooling method,

I1 accordance with the present invention the propcllent vapor is superheated between of a heating coil .13 surrounding the nozzle 2 and supplied with'thecurrent from suitable source-14. An insulating coupling 16 .is preferably provided between the nozzle I and duct 5'anol suitable insulation 17 (e. g.

lava) is placed-around the coil 13 to localize the heat in the nozzle. When. employing mercury 'vapor as the propellant and water .vapor as the, refrigerant the mercury is preferably heated to a temperature of the order of 600 CZ" -By applying-an auxiliary source of heat, such as; 13, to the mercury vapor, instead of applying all the heat in the boiler 8, all of the aforesaid advantages of superheated propellent vapor maybe at-' tained. without creating an excess of pressure of the mercury vapor in the boiler. Consequently the height of mercury in conduit 7 required to balance the vapor pressure in the boiler may be kept low, Whereas if all the heat were applied in, the boiler there. would be created a vapor pressure so high that .the h'eight ofconduit 7 would be so excessive as to render the apparatus inapplicable to, many a situations; and also the density of the vapor would be so great that a nozzle of a practical size would deliver an excessive amount of mercury vapor.

The boiler .is preferably constructed so that variation in the height ,of the liquid therein produces a high variation in the rate of evaporation. This is accomplished inthe particular embodiment illustrated in the drawings by making the cross-sectional area of vthe liquid space surrounding the vertical heater 15Icdmparatively small so that asthe level of the liquid falls less of the heater projects below the level of "the liquid ap'd the heater is therefore comparatively 1nefliective' in'producing evaporation. f Thus as the pressure in the boiler builds up the level ofthe liquidin the boiler falls and the'rate of evaporation decreases.

rate of evaporation is automatically adjusted tothe requirements of the apparatus. As herein used the term gaseous fluid is "intendedto comprehend any vapor (as' well asanyfgas) whether the vaponis above or below its critical-temperature. I laim: a 7 1. A method for aspirating a gaseous fluid by means of a-propellent substance which com rises vaporizing the substance, superheating the vaporized substance to increase the molecular velocity of the vapors and aspirating the gaseous fluid by means of the superheatedyaporsu p by means of a propellent vapor which comhaving .a molecular weight greater than that- .of the gaseous fluid by superheating the proa and aspirating the gaseous fluid by means of J aspirating the gaseous ,Sflld superheated vapors and thereafter con 'fluid by means of 2. A method for aspiratinga gaseous fluid prises vaporizing a substance to form the f propellent vapor,

superheating the vaporized substance-to increase itsmolecular velocity to approximately. that 'ofthe gaseous fluid, fluid by'means of the de'nsing'the saidvapors. J

A method for aspirating agaseous. a propellant vapor having a molecular'weight greater than that of the gaseous fluid which comprises increasing the molecular velocity oi a pr'opellentvapor pellent vapor at substantially the .point at which the gaseous fluid is to be aspirated,

\ T the superheated vapors.

- frigerant materials bymeans of the superheated vapor 4.; a refrigerating system a method of cooling theirefrigerant liquid material which compr ses aspiratingthe vapors of the reof a propellent substance .having a molecular weight greatertthan that of the vapor of the refrigerant material, con- 7 and caus" rating substance to the aspirator,

1 substance before-said gaseous densing'the combined vapors of the refriger ant material and the propeller' t substance I independent recirculation of both. the re igerant material and the propellent'substance.

a 5.'In an apparatus of the character described, the combination of an aspirator andmeans for continuously circulatingan aspicomprising a vaporizerforvaporizmg said substance, means for 'superheating the wipers of said 7 uid aspirated thereby, means for condensing the vaporsof said substance and means for re.-

turning .said' condensed substance to said In this way the vaporizer rator.

6. In an apparatus of the character described, the combination of an aspirator, a vaporizer for vaporizing a propellant sub-' during the operation of the aspivstance, means for conducting the'vapors of said substance to said aspirator, means for superheating the vapors Of'SaId substance at the inlet to the aspirator to increase the -molecular velocity of the .pro

Vfor stlperheating the propellent vapor afte being evaporated in said boiler.

8. In apparatus of thecharacter described "employing a refrigerant vapor and a pro-' having greater molecular a condenser,a'n evaporator,

pellent vapor weight, a boiler, a propellent vapor duct leading from the boiler to the condenser, an a'spirator in said duct, a refrigerant-vapor duct leading from the evaporator to said aspirator, anda superheater for increasing the molecularvelocity .of the propellent vapor to approximately that of the'refrigerant vapor.

9. In apparatus of thecharacter described, a boiler containing mercury, an evaporator llent sub-- duct leading from the containing a lighter refrigerant, a mercury vapor duct leading from the boiler to the condenser, an aspirator in said duct, 21' refrigerant vapor duct leading from the evaporator to said 'aspirator, and a superheater 'for increasing the molecular velocity of the -mercury vapor to approximately that of the refrigerantvapor, v

.10. In apparatus of the character described, a boiler containing mercury, an evaporator containing vwater, a mercury vapor duct leading from the boiler to the condenser, anaspirator in said duct, a water a vapor duct leading fromjtheevaporator to said aspirator, asup'erheater for increasing the molecularvelocityof the mercury vapor vto approximately that of the refrigerant vapor, and. means for superheating the'mer;

vapor to approximately 600 C. ed .by me at Boston,Mas s.,this 28th I day of'Augu'st1924. v- F;

v CHARLES G. 

